Jeb Bush Slams Trump in New Ad

CHARLESTON, SC -- The political ad wars are in full effect.

In advance of tonight's Republican debate, and less than a month before primary and caucus voting begins, Jeb Bush's campaign has released a new ad attacking rival Republican Donald Trump for apparently mocking a disabled reporter.

The ad, titled "Enough," is now airing in New Hampshire and is part of the campaign's rotating $4.6 million ad buy in the state.

It begins with a mock Google search, "Donald Trump is a jerk," and leads to sound from one of Bush's town halls, in which he said, "Just one other thing, I got to get this off my chest: Donald Trump is a jerk."

This ad attempts to explain why he made the comment. Since he first made those New Hampshire remarks last month, Bush has defiantly defended them.

The ad then borrows sound from Bush's remarks at a town hall in Meredith, New Hampshire, last week.

"I think life is truly a gift from God ... and when anybody disparages people with disabilities, it sets me off," he said. "That's why I called him a jerk. What kind of person would you want to have in the presidency that does this?"

The comments are related to Trump's apparent mocking of the New York Times' reporter's muscular disorder in November. Trump has insisted he does not know the reporter, Serge Kovaleski, and was unaware of his condition.

The ad shows footage from Trump's apparent mocking of Kovaleski in a split-screen with a photo of Kovaleski.

Kovaleski has disputed Trump's claim and said he was on a first-name basis with the real estate mogul when he covered him for the New York Daily News in the 1980s.

Attempting to assail Trump's character has become a common refrain for Bush while out on the campaign trail. Bush's campaign often claims they are among only a few candidates going after Trump in such a fashion.

"Everybody else is in the witness-protection program," Bush recently said in Iowa. "I'm the only guy that wants to defend the conservative cause against a guy who's not a conservative."

Such an attack is likely to surface in tonight's debate, his advisers told ABC News. As Bush has polled among the lowest of those candidates participating in the main stage debate, his position is on the outer corners of the debate stage, no longer directly next to Trump, the front-runner, as he once was.